Stacy Peralta has made two of the decade's best documentaries in "Dogtown and Z-Boys" and "Riding Giants," exhilarating, informative works with reverence for the cultures (skateboard and surf, respectively) they chronicle.

With the sobering "Crips and Bloods: Made in America," Peralta ventures outside subjects of personal expertise, tackling the gang war that has long convulsed Los Angeles' African American community. Opening with a stunning aerial shot of an upside-down L.A. skyline, then tracking to neglected South Los Angeles, it shows the battle lines behind which gang members have imprisoned themselves.

The film works best as a history lesson of the L.A. black experience, arguing that economic neglect, institutional racism and covert government operations fueled the 1965 and 1992 riots and created the leadership vacuum in which gangs took root. More problematic -- maddening, really -- are interviews with former and current gangbangers about their daily lives, fashion sense and feelings about the endless cycle of pointless bloodletting they seem to hate but are unwilling or unable to stop. Despite the obligatory gang violence-prevention sequence, no impression is left that anything will improve. As one Crip observes, "It is what it is."